Conventional heat exchangers are fitted with several supply pipes carrying a heat transfer fluid for feeding a distribution system with heated heat exchanger fluid, such as, for example, hot water or steam. While this heated fluid passes through the heat exchanger pipes, some of the heat transfers to the medium flowing around the heat exchanger. When the heat exchange fluid has cooled down, which can be in condensed form if steam is used, it is drained off through a collecting system having a drainage pipe at the other end of the heat exchanger pipes.
The distribution system for the heat transfer fluid is usually positioned at one end of the heat exchanger pipes. The location of the distribution system makes the heat exchanger pipes not easily accessible, such as, for example, for cleaning or repair. Furthermore, the transverse distribution pipes reduce the free passage cross-section area and obstruct the flow of material through the heat exchanger. The obstruction of flow around the heat exchanger is particularly pronounced when the material to be dried flows perpendicularly onto the distribution level. If this type of heat exchanger is used in fluidized-bed drying plants, at least the top section of the heat exchanger is located in the fluidized bed, to which the heat from the heat transfer fluid is to be conveyed. The distribution system here seriously obstructs the flow of the medium that fluidizes the fluidized bed, thus obstructing the flow of the fluidized bed itself. Since there are distribution pipes in the fluidized bed, there is a danger of the material being dried building up on the heat exchanger, which is aggravated by the narrowing of the flow passage cross-section areas.
Accordingly, there is a continuing need in the industry for a heat exchanger that does not restrict the flow in a fluidized bed.